Hi, here is the ERC-20 address of a Binance account on Etherescan.
Now I have 0 clue where these coins are, they are not in the binance wallet...
that means you have not yet bridged it. If you wanna convert your asset from ethereum chain to the bsc chain and you must have bridged your asset or at least sending it from binance exchange site with in BEP20 form.
Could I have send them from BSC chain to Erc-20?
You have needed to bridge it or when you didn't bridge it and you will be only sending your ERC20 asset to the another ethereum address and it will never arrive to your binance chain wallet.
Where can they be and how do I recover them?
have you checked your address through this site?
https://bscscan.com/If you have bridged it and then your binance smartchain wallet will able receive your asset.